1. Field of the Invention
The invention relates to a closing device for a body part pivotably mounted on a base part having a spring element including a piston rod which is axially moveable in a cylinder and a cable device which engages the body part.
2. Description of the Related Art
FR 2 717 215 A1 describes a closing device, in particular for a body part on a motor vehicle, the body part being mounted pivotably on a base part and a pneumatic spring element having an axially moveable piston rod, as a first subassembly, within a cylinder, as a second subassembly, which exerts a closing force on the body part via a cable device, which engages on the body part.
In the exemplary embodiment according to FIG. 3, the cable device comprises two subunits which are actuated in the tension direction by the gas-filled spring. The vehicle flap pivots in the closing direction to the same extent as the piston rod is moved. For an effective transmission of tensile force, the two subunits have to be coordinated with each other exactly in terms of their length, since otherwise only one of the two subunits is tensioned by the pneumatic spring element.
In the variant according to FIG. 4, the cable device is of single-part design. One end is fastened to the body and the second end is fastened to the piston rod of the pneumatic spring element. Deflection pulleys on the pivotable body part ensure that an axial movement of the piston rod of the pneumatic spring element is converted into a pivoting movement of the body part. In the case of this construction principle, there is the serious disadvantage that the stroke movement of the piston rod is converted into a pivoting movement of the body part only in the ratio of 2:1. Consequently, a corresponding long, pneumatic spring element has to be used. However, there is virtually no suitable connecting point for this, in particular in the region of the trunk in a motor vehicle.
The object of the present invention is to realize a compact spring element for a closing device.
According to the invention, the object is achieved by the spring element having, on its axially moveable subassembly, a deflection pulley over which the cable device is guided, the end of the cable device being connected in a positionally fixed manner with respect to the other subassembly.
The effect achieved by the axially moveable deflection pulley for the cable device is that the ratio of piston-rod movement to pivoting movement of the body part is 1:2. The fitting of an extremely short spring element is therefore possible.
For this purpose, the piston rod has a connecting head to which the deflection pulley is fastened.
According to a preferred embodiment, a stop which is effective in the retraction direction of the piston rod is formed between the two subassemblies of the spring element. A stop between the body part and the base part is rendered superfluous. Furthermore, there can be more variation with regard to the technical configuration of the spring element, since it is not necessary for a given spring force to retain the body part in a defined rest position.
In a further advantageous refinement, the connecting head has the stop. The stop is freely accessible in the event of any repairs.
In particular in order to protect the cylinder and in order to minimize noise, the cylinder has a counter stop on which the stop comes to rest.
In order to simplify the installation, the positionally fixed end of the cable device is fastened to a securing means which supports the spring element.
Furthermore, provision may be made for the effective length of the cable device to be adjustable by shifting the positionally fixed end. By this means, a certain position of the pivotable component with respect to a desired extension position of the piston rod of the spring element can be set. Furthermore, if a second cable device which is independent of the first cable device, which interacts with the spring element, is used, both cable devices can be matched in their length for the purpose of compensating tolerances.
For this purpose, the positionally fixed end of the cable device is retained by a fixing sleeve which is mounted in a manner such that it can be adjusted. For example, the fixing sleeve has a threaded section which engages in the securing means for the spring element. In this case, the positionally fixed end of the cable device is guided through the fixing sleeve and can move in the circumferential direction with respect to the fixing sleeve, so that a torsional movement is not introduced into the cable device when the cable device is adjusted.
In one embodiment, the cable device engages on the moveable body part at two supporting points and, at a predetermined angular position of the body part, two sections of the cable device exert a supporting force, with a stop device, as part of the cable device, being in engagement during the closing movement owing to the spring force of the spring element. The effect achieved is that, firstly, the favorable stroke/body-part movement ratio is maintained and, secondly, two supporting points can be used, with the result that the introduction of force into the body part can be undertaken more favorably.
In addition, the stop device can have a stop ring which can be displaced axially on the cable device in order to adjust the stop device. By this means, freedom from play within the closing device during the closing movement is achieved.
As an alternative, two spring elements arranged parallel in their function may also be used, with a single cable device being connected to both spring elements. The favorable movement ratio of spring element and body part is also achieved in this variant. The freedom from play within the closing system arises automatically, since the two spring elements prestress the cable device owing to the directions in which their forces act.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.